Electric cut-out.



UNITED STATES PATENT OFFICE.

HENRY NOEL POTTER, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO GEORGEWESTINGHOUSE, OF PITTSBURG, PENNSYLVANIA.

ELECTRIC CUT-OUT.

SPECIFICATION forming part of Letters Patent No. 714,607, dated November25, 1902. Application filed March 27, 1901. Serial No. 53,033. (Nomodel.)

To aZZ whom it may concern:

Be it known that I, HENRY NOEL POTTER, a citizen of the United States,and a resident of Pittsburg, in the county of Allegheny and State ofPennsylvania, have invented certain new and useful Improvements inElectric Cut- Outs, of which the following is a specification.

My invention relates to improvements in cut-outs designed to be used onalternatingcurrent circuits, and it is applicable to all cut-outs whichare subjected to the conditions that obtain in such circuits.

For the sake of convenience I shall describe my invention as applied toa cut out for Nernst lamps. In operating cut-outs for this class oflamps designed 'to operate on all frequencies-such, for example, asthree thousand alternations per minute-difficulty has been found inpreventing a noise being produced by the vibration of parts. Owing tothe need of securing great freedom of movement in such cut-outs, thebearing or bearings of the moving part must be very loose. In the caseof an immovable pin surrounded by a collar attached to the moving partthe opening in the collar is generally made considerably larger than thediameter of the pin. Unless means be provided for preventing it a shortdiametral motion of the collar relative to the pin during the periods ofweak magnetic attraction may take place by reason of the intermittentmagnetic pull and gravity being opposed to each other. In other words,if the angle between the line of magnetic attraction and the downwardpull of gravity exceeds ninety degrees the intermittent effects of themagnetic force and of gravitation will cause the collar of the movingpart to bump up against the pin on one side and then fall away from itand bump against the other side, thereby making a noise. To preventthis, the magnetic force and the gravitational restraining force shouldhave their pulls exerted at an angle with each other of less than ninetydegrees-that is to say, as gravity pulls the moving part downward themovement due to the magnet should be slantingly downward. By organizinga cut-out apparatus so as to produce this relation of forces the noiseof the cut-out-can be prevented.

The invention which I have thus indicated was first suggested to me by arecognition of the fact that all moving parts either have a period oftheir own, which causes them to be resonant at the frequency employed,or else their natural period is so short in comparison to the durationof one alternation that they are able to execute considerable movementbetween alternations. It therefore seemed to me to be possible tocorrect this tendency by giving to the moving part or parts of a cut-outapparatus a natural period, which should be long in comparison to theduration of one alternation. This lengthening of the period of themoving armature can be easily accomplished on the general principle ofthe metronome-in other words, of an oscillating body having its centerof gravity but slightly below the center of support and having aconsiderable portion of its weight relatively far above the center ofsupport. Even short pendulums so constructed may be made to have verylong periods. In the cut-out the slight stable equilibrium of themetronome is not necessarily incorporated; but the combination may beput in unstable relation by placing the center of gravity above thecenter of rotation and support.

The period of the moving part can readily be made variable by means ofan adjustable weight, which can be set at varying distances from thecenter of oscillation. In this way the natural period of the cut-out canbe made incommensurable with any particular frequency on which the lampmayhave to operate.

I My invention will be fully understood by reference to the accompanyingdrawings, in which Figure 1 is a diagram of a system of Nernstlampcircuits including my improved cut-ou t, which is shown in elevation.Fig. 2 is aview, partly in section and partly in elevation, of myimproved cut-out adapted to control both sides of the circuit. Fig. 3 isa detail view of the contacts employed with the form of apparatusillustrated in Fig. 2. Fig. 4 is a diagram of the circuits controlled bythe cutout illustrated in Fig. 2; and Fig. 5 is a view, partly insection and partly in elevation, of a cut-out of the same general typeconstructed strictly on the metronome principle.

Referring to Fig. 1,- the elements 1 and 2 are respectively a glower ofthe N ernst type and an electric heater therefor arranged in proximityto the glower, these elements being connected up in parallel between twomain conductors 3 and 4:, supplied by any suitable source of alternatingcurrent. In series with the glower is arranged the coil of anelectromagnetic cutout, and in series with the heater are arranged theterminals 6 and 7, whose relation is controlled by the electrom'agnet ofthe cut-out. The coil referred to is designated by the character 5. Thefunction of the cut-out apparatus in this class of circuits is to breakthe circuit of the heater when the glower has become conductive throughits operation.

The part 6 is in the present instance a sta tionary terminal in the formof a bent piece of metal secured by screws 8 8 to the insulating-head 9of the magnet 5. The part 7 is the movable part of the cut-out, and itconsists, essentially, of a pivotedbar of iron hav ing a rod 10 securedto it beyond the pivot by means of a screw 11 or some other suitabledevice. A weight 12 is adjustably secured to the rod 10 by means of aset-screw 13. The parts 7 and 10 may, if found convenient, be made in asingle piece, and the weight 12 may be made adjustable upon the rod 10in any other convenient way besides the one indicated.

The part 7 is pivoted upon a transverse rod or pin 14, the opening inthe part 7 being somewhat larger than the pin and constituting a collarloosely surrounding the pin. Before the glower begins to operate the endof the terminal 7 rests against the stationary terminal 6, theheater-circuit being thereby completed. It will be understood that thepart 7 is of soft iron and that its end lies within the range ofinfluence of the iron core 15 of the magnet 5.

When the glower becomes conductive and the glower-circuit is therebybrought into operation, causing current to pass through the coil 5, themagnet will be energized and the movable terminal 7 will be drawn downinto the position illustrated in Fig. 1, whereby the heater-circuit willbe broken.

It will be remembered that the glower-circuit, including the magnet 5,is now traversed by a rapidly-alternating current, tending to energizethe magnet at the summit of each alternation and to leave the movableterminal 7 wholly under the influence of gravity between alternations.It will also be noted that with the arrangement shown and described thepull of the magnet-core is slantingly downward, while the action ofgravity is directly downward. Accordingly there is no tendency toward adiametral movement of the collar surrounding the pin upon the pin thanwould be the case if the action of the magnet were in a directionexceeding ninety degrees from a direct downward pull. Should theadjustment prove to be such that there is still a disagreeablevibration, the period of the moving part of the cut-out can be varied bya proper adjustment of the weight 12 upon the rod 10 until suchvibration ceases to produce a noise.

The cut-out shown in Fig. 1 is a single-pole cut-out. In Fig. 2 I show adouble-pole cutout adapted to operate on the same general principle.Here the weight 12 is screwthreaded to correspond to the screw-threadedform given to the upper end of the rod 10, and two moving parts areprovided, one on each side of the magnet 5. In the lower insulating-headof' the said magnet, on opposite sides of the core 15, are mounted twopairs of contact-terminals 16 16, and the part 7 on each side isarranged to bridge one of these pairs. I generally surround the ironportion 7with a band 17, of silver or platinum, to prevent oxidation atthe points where the movable element of the cut-out makes contact withthe stationary terminals. The parts 7 in this construction are providedwith transverse pins 14 14, which are mounted in suitable eyes 18 18 inthe outer ends of suitable yokes 19 of non-magnetic material.

The core 15 is provided with a screw-threaded downward extension 20,which, in conjunction with a suitable nut 21, serves as a means forattaching the core and the magnet to an insulating-base 22. Between thebase and the main body of the core 15 the yokes 19 are mounted, and alsoa soft-iron pole-piece 23, the latter being screwed upon the extension20. The yokes 19 are secured to the pole-piece 23 by means ofscrew-bolts 24 24:, or they may be held in place between the pole-piece23 and the base 22 by tightening the nut 21. Normally the movable partsof the cut-out are so held by gravity that the rings 17 17 are incontact with the stationary terminals 16 16. When, however, currenttraverses the glowercircuit, including the coil 5, and the polepiece 23is magnetized, the ends of the parts 7 are drawn down into the positionillustrated in Fig. 2, whereby the heater-circuit is broken on bothsides. This will be more clearly evidenced from an examination of Fig.4., which is a diagram of the circuits designed to be used with such acut-out as has just been described. In this diagram I have shown aplurality of glowers 1 1, each in series with a suitable ballastresistance 25, the coil 5 being in a circuit common to all the glowers.The diagram shows the heater-circuit broken, it being assumed that theheater has already done its work and that the glowercircuit is now inoperation.

In Fig. 5 I have illustrated a form of cut-- out more nearlycorresponding in principle and action to a metronome. Here the movablepart is mounted upon a suitable pair of bent insulating-arms 26, theconstruction of the entire movable part being such that its center ofgravity (indicated at 27) is below the center of rotation. Thepole-piece 23 is IIO extended, as shown, far enough so that its sphereof influence embraces the lower'end of the part 7, while the stationaryterminal 6 of the cut-out is mounted directly upon the base 22 by meansof a screw-bolt 28 and a nut 29. The magnet 4 is held to the base bymeans of a screw 30 entering the base from below and passing up into ascrew-threaded opening in the core. The action is obvious.

The invention claimed is 1. In an electromagnetic cut-out, a movableelement, having an adjustable natural period, and so disposed that theforce of restraint and the pull of the magnet are at an angle of lessthan ninety degrees with relation to each other.

2. In an electric circuit, carrying an alternating current ofdeterminate frequency, an electromagnetic cut out having a pivoted HENRYNOEL POTTER.

Witnesses:

WM. I-I. CAPEL, GEORGE H. STOOKBRIDGE.

